Need advice on floor joist repair

[Hillyard]

Hello everyone,

I was running an additional cat6 run in my crawl space and happened to notice a problem with one of my 2"x10"x12' floor joists (The shortest of all the floor joists). It has a split running parallel with the grain but it has shifted over on the bottom about 3/8"-5/8". The split runs for about 15" and the shifted portion is about 8-10" on the end towards the rim joist. I'm worried because the shifted portion is sitting on the perimeter rim joist.

I want to fix it but wanted to make sure I was doing the right thing. I plan on putting 4' sections of treated 3/4" plywood running along both sides of the floor joist. Then I wanted to hold it in place with about 3 or 4 carriage bolts and liquid nails. Finally, I wanted to box it in and use a piece of 2x10 to sit parallel with the rim joists on both sides so it can't flex and kick out.

When I pulled the fiberglass insulation back from the rim joists it had a small amount of mold/fungus on it. I'm assuming the previous homeowner added fiberglass insulation without a kraft facing. I have a huge roll of insulation bubble wrap that my father gave me after he had a metal barn roof installed. Would that work as an acceptable air barrier? I would just plan on rolling it out slitting it where a joist is and then stapling it. I know the best option is to cut foam squares out and place them on the rim joists between the floor joists but the fiberglass insulation looks fairly new.

Thanks,
Zach

 

[kd3pc]

you really should "sister" in a new joist, if at all possible. Else your box may do OK.

As to the mold, in our area - you either insulate and seal and heat the crawl space OR you have no insulation and leave the crawl space to seasonal temp changes. Else you get mold between the insulation and the subfloor on the crawl space side. It matters not whether you have kraft face or just insulation. The moisture has to go somewhere, if it is not conditioned and removed (see the insulate and condition crawl space above)

I have seen houses less than two years old with mold and rot already where insulation has been stuffed between joists on a crawl space.

My house is two years old, and is on a crawl space, with plastic on the grade and all my HVAC ducting is in the crawl space, and several times a year I get condensation that will leave puddles on the plastic. Foundation vents are wide open. I spray twice a year with bleach and dry things out between seasons.

There are tons of companies that "mitigate" this and will totally seal your crawl space, put some ducts in there and you pay to heat/cool that added space. I was not big on exchanging air between living space and crawl space, and the cost is HIGH - so I do it my way. I do have chilly floors when AC is on, but warm when the heat is on.

best of luck, what ever you decide.